Publishing their findings in PLOS ONE, researchers gave the Viekira regimen to 144 people with HIV and genotype 1 of HCV.

Following treatment, 41.7 percent of the participants saw their estimated glomerular filtration rate (eGFR, an indication of kidney function) decline by 5 percent or more. Sixty-five percent of those who experienced such a reduction maintained the decline 12 weeks after completing treatment.

The median decline in eGFR, however, was only 2 milliliters per minute, which the study authors stated had “doubtful clinical significance,” meaning it was unlikely to be associated with actual medical problems.

Factors associated with a decline in eGFR during the study included living with HCV for longer than 12.9 years (2.9-fold greater likelihood of a decline in eGFR); having a hep C viral load below 1.97 million (3.5-fold greater likelihood); and having a platelet count below 167,000 (2.8-fold greater likelihood).

Additional factors associated with a decline in eGFR included being treated with Viread (tenofovir disoproxil fumarate), ribavirin or HIV integrase inhibitors, living longer with HIV, having been treated for HCV before and being older.